Production of sheet metal



Patented May 2, 1933 UNITED STATES PATENT OFFICE JOHN C. WILLIAMS, OF STEUBENVILLE, OHIO, JOHN STEWART WILLIAMSON AN D JOSEPH ECHOLS, OF WEIRTON, WEST VIRGINIA, AND CLINTON H. HUNT AN D GEORGE W. V'REELAND, OF STEUBENVILLE, OHIO, ASSIGNORS TO A. CORPORATION OF DELAWARE WEIR-TON STEEL COMPANY,

PRODUCTION OF SHEET METAL No Drawing.

This invention relates to the production of sheet metal, and specifically sheet steel, and the object in view is the production of sheet material such in quality and character 5 as to be suited in superior degree to the demands of the industries: the automotive industry, for instance, the furniture-making industry, and the enameling industry. lVhat is needed is a sheet of sufficient strength, capable of being shaped between dies, and possessed of a surface of such character and quality as to be responsive to the shaping instrumentalities; such as to take a surface finish and to present in the finished article a surface of unblemished uniformity and great ductility.

Of late years, in response to the demands of economy, such material'has been produced on continuous sheet mills or on continuous strip sheet mills, and the usual procedure is this: Slabs, being produced, are reheated, and then by continuous hot-rolling reduced to an intermediate gauge. At this stage, usually after roller-leveling (a step which may or may not be necessary), the material is pickled, to remove the scale and oxide. The material then is cold-rolled approximately to final gauge, cut to length, normalized, and pickled. Pickling at this stage, however, may or may not be requisite, and its practice depends on the specifications for the ultimate product. The sheets then are box-annealed, and (if the ultimate requirements necessitate) again pickled. They then are given one or more tempering passes by cold-rolling, and are prepared for the purchaser by shearing, resquaring, slitting, patent leveling, oiling, etc.

The normalizing of sheet material is a heat-treating procedure which differs from ordinary annealing in that the material is raised to and cooled from a much higher maximum temperature, with the consequence and effect that the pre-existing crystalline structure of the material is changed into a structure of equi-axed grains, with a redistribution between grains of the carbon, whether free or combined. Normalizing increases greatly the ductility of the material.

The described method of manufacture,

Application filed October 14, 1930. Serial No. 488,694.

superior though it is to the old sheet-mill method of production, particularly in that it effects large economies, still is not wholly satisfactory: the product still is not wholly suited to its intended uses. Particularly cold-rolling produces a bright, smooth surface, and in consequence, during the annealing operation, as the temperature comes to a maximum, there is a tendency of superposed lengths to adhere over their smooth and contacting surfaces. In endeavoring to prevent this, the temperature may in the annealing operation be unduly held down, with the consequence and effect that the finished product may be lacking in softness and ductility. Furthermore, the bright,

smooth surface afforded by the method now generally preferred is objectionable, in that in the die-press the surfaces of the material slip too easily upon the die surfaces; it is difiicult for the dies. properly to grip the material, Still further, the operation of cold-rolling, lnstead of eliminating small surface defects, tends rather to accentuate them and to give them permanence in the finished sheet. The pickling operation also of the now generally preferred procedure gives to the sheet the undesired quality known as acid brittleness. It is to the avoidance of these difliculties and their consequent imperfections that the present invention is particularly addressed.

In the practice of this invention the hotrolled material of intermediate gauge, flattened if desired, is not pickled. Instead, it is sand-blasted. It then is cold-rolled approximately to ultimate gauge, normalized, and again sand-blasted. Then it is cut to length, and the lengths are box-annealed temper-rolled, and prepared for the market by shearing, resquaring, oiling, etc.

The modification of procedure is found in a substitution of sand-blasting for pickling. In the preferred procedure, the cooled material, as' it emerges from the normalizing apparatus, is again sand-blasted, and then it is cut to length.

We have used the term sand-blasting to designated a step in the procedure which admits of considerable latitude in detail, and

we mean to include in the term all the range of variation indicated herein. In this step the surface of the metal is sub'ect to a blast of fluid, conveniently air, whic carries particles of suitable abrasive, such as quartz sand, steel grit, shot, or other hard material; and the effect is two-fold. It consists, first, in the removal of scale and oxide from the surface of the sheet; and, second, in a consolidation of the metal surface in the peening effect of the impacting particles.

This sand-blasting is preferably performed upon both sides of the sheet.

.The advantages of removal of scale and oxide by sand-blasting over removal by pickling are uniformity of surface; a surface of velvety texture and of superior quality for the further operations, and a surface which, even after ensuing cold-rolling, is

of superior quality; and the avoidance of.

the condition of sheet termed acid brittleness.

The resulting sheet has the advantages over the sheet as now usually produced that its surface is such as to be easily grasped and held by forming dies; its surface is such as to take and hold surface finish, of paint, enamel, etc.- the particles of abrasive removes such surface imperfections as pits, slivers, light scratches, and light seams, and reclaims otherwise defective material. Acid brittleness is avoided and, other things being equal, the product of this invention is superior, for it may be used in more diflicult stamping and deep-drawing operations.

to one or more light cold-r0 necessarily associated with An alternative procedure to that already described, and still involving the practice of this invention, is, after the cold-rolling of the material to gauge, to normalize, then box-anneal, and then. sand-blast. After sand-blasting the material ma be subject 1 passes, in order to impart to it the proper temper.

Another alternative is to normalize, and, omitting box-annealing, immediately after normalizing, the material one or more light, cold-roll, tempering passes, or (alternatively, and to produce the same effect) to subject the material to the action of a roller-leveler,

The invention in .broader aspect is not normalizing although ordinarily it will be practiced upon a normalized sheet or in association with the procedure of normalizing a sheet. That is to say, in the production of a sheet of iron or steel the material is brought to substantially its ultimate gauge by cold-rolling and it is the cold-rolled surface. with its inherent imperfections which engages our attention. That cold-rolled surface, being sand-blasted, is improved in those respects which we have in mind and made ready for fabrication. The sand-blasted material may receive treat.-

The minute peening effect of to sand-blast; then to give to ment in the way of annealing, cold-rolling, and the like, to give to it the desired temper.

We claim as our invention:

1. In the production of sheet iron and sheet steel the method herein described which consists in performing upon the material the ensuing steps in the order named: hot-rolling to intermediate gauge, removing the scale from the surfaces of the rolled material, cold rolling to approximately ultimate gauge, normalizing, sand blasting, and temper-finishing.

2. In the production of sheet iron and sheet steel the method herein described which consists in performing upon the material the ensuing steps in the order named: hot-rolling to lntermediate gauge, sandblasting the surfaces of the rolled material, cold-rolling to approximately ultimate guage, normalizing, sand-blasting again, and temper-finishing.

In testimony whereof we have hereunto set our hands.

JOHN C. WILLIAMS. CLINTON H. HUNT. GEORGE W. VREELAND.

J. STEWART WILLIAMSON. JOSEPH ECHOLS. 

